GregH during WW2 when I was being trained as an Infantryman in the British Army, in Corps training after firing our rifles we had to boil out the barrels as the ammo was very corrosive, however by the time it became my turn the water was just about luke warm, and when overseas didn't ever remember using anything except the Pull-through. The unit to use the hot water was a metal funnel with one side flat so as to access the chamber. Later in Battalion training knowing more about ammo, we had two types of rounds for the . 303 Lee Enfield, both was the rim kind, and the marking on the rim was V11 and the other V11*. The former was cordite and the second was a silver, grey powder kind. We were told the name of the powder it but didn't take much notice, as the V11* could not be used for overhead firing and not for frontline duty. It was called 'Empire' ammo as one didn't know what country manufactured it. It was probably much cheaper than cordite, or perhaps it could be manufactured in greater quantity at the time.
Incidentally about 1/3 of the Enfield rifles in the Platoon had, US Property stamped on them, they only differed in manufacture, with a cut-out to remove the bolt from the rifle, whereas the others had a spring catch to depress to free the bolt, also the US Property ones had an extra grove in the rifling
The British just use the Broad Arrow, three strokes like a bird print to identify British government property.